Abstract
Effects of Mg, Si content, additional elements and pre-aging temperatures on the bake-hardenability of Al–Mg–Si alloys were investigated by tensile tests and an electron microscope. The 0.2% proof stress obtained by the short time aging at 170°C increased with increasing Mg2Si content, and it became higher with the following ascending order: pseudobinary system alloys <excess Mg alloys <excess Si alloys. The pre-aging at 100°C was more effective in increasing the bake-hardenability of the alloys than that at room temperature. The additions of Ag, Cu, Zn and Sn on the bake-hardenability of the Al–0.8%Mg2Si–0.5%Si alloy were ineffective, on the contrary the addition of Mn or Cr was effective. The Al–0.8%Mg2Si–0.5%–0.1%Mn (or 0.1%Cr) alloy was found to be the most appropriate for automobile body panels.
